In many processing and computing systems, magnetic data storage devices, such as disk drives are utilized for storing data. A typical disk drive includes a spindle motor having a rotor for rotating one or more data disks having data storage surfaces, and an actuator for moving a head carrier arm that supports transducer (read/write) heads, radially across the data disks to write data to or read data from concentric data tracks on the data disk.
In general, a magnetic transducer head is positioned very close to each data storage disk surface by a slider suspended upon an air bearing. The close proximity of the head to the disk surface allows recording of very high resolution data and servo patterns, on the disk surface. Servo patterns are typically written with uniform angular spacing of servo sectors and interleaved data sectors or blocks. An example servo pattern includes circumferentially sequential, radially staggered single frequency bursts. Some servo patterns provide the disk drive with clock information or head position information to enable the actuator, such as a rotary voice coil motor to move the head from starting tracks to destination tracks during random access track seeking operations.
The servo clock pattern is typically written to a disk at a point in the drive assembly process before the hard disk unit is sealed against particulate contamination from the ambient environment. For example, the clock pattern may be written at the manufacturer's location using a servo track writer (STW) machine.
However, the present state of adjusting the radius for the clockhead servo writer is significant and costly in both time and manufacture. For example, presently the clockhead is installed in the STW machine and must be replaced after it has written an established number of clock patterns on hard disk drives, fails in operation, or the like. After the clockhead is installed, an actual head disk assembly (HDA) is mounted on the STW machine. The clockhead writes the clock pattern on the HDA and the HDA is dismounted and disassembled. The disk is cleaned with soap and water and then the disk surface is coated with a ferrofluid and allowed to dry. When dry, the ferrofluid solution becomes visible and the clock pattern can be viewed and measured through a microscope.
The clockhead is adjusted based on the measurements and the process is repeated with another HDA until the measurements of the clock pattern are within tolerance. At that time, the clockhead is used to write the clock pattern on HDA's during the manufacturing process until the life of the clockhead is complete, or failure occurs. Then, a new clockhead is installed in the STW machine and the calibration process is repeated.
Thus, the present method for calibrating the clockhead in the STW machine results in an actual HDA, or components therein, being discarded or rendered to scrap. In addition, the process is tedious and time consuming. The present method also generates waste in the form of electrical, chemical, component, manufacturing time and manpower. There is also significant lost manufacturing time during the downtime associated with the clockhead calibration process.
A method for streamlining the process and reducing manufacturing costs, waste and time is desirable.